


Finding Evidence

by PineTrain



Category: Gravity Falls
Genre: F/M, Masturbation, Multi, Pinescifica, Voyeurism, pinecest - Freeform
Language: English
Status: Completed
Published: 2017-06-01
Updated: 2017-06-01
Packaged: 2018-11-07 21:51:24
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 4,328
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/11067846
Author URL: https://archiveofourown.org/users/PineTrain/pseuds/PineTrain





	Finding Evidence

 

Based on [these](https://samson-art-blog.tumblr.com/post/161077341986) [three](https://samson-art-blog.tumblr.com/post/161089522361/is-she-filming-them-for-blackmail-or-does-she) [pictures](https://chillguydraws.tumblr.com/post/161084952333/pacifica-is-simply-partaking-in-her-cuckold).

* * *

 

Pacifica grumbled to herself as she hesitated just around the corner of trees that would bring the Mystery Shack into view. She couldn’t believe she’d walked all the way here instead of driving. What was even more frustrating was that this wasn’t the first time she’d done it. She slapped her cheeks a bit and continued walking, determined to finally keep going after chickening out so many times before.

She just had to know if they were doing it. If the twins were actually committing incest. They were so close, and she swore she saw a ton of hints, but was she just imagining? Did she just think they were together in that way because she found the idea hot? She could never fully decide either way, whether her suspicions were right or wrong. Everything was just so vague, partially due to her reluctance to fully commit to investigating.

Well, now she had. She was going to get to the bottom of this no matter what. Pacifica flushed as she marched towards the Shack, both in embarrassment at how much she hoped she was right, as well as due to the realization she wasn’t likely to be a successful spy with how obvious her approach was coming down the road. Goddammit, planning things would be easier if she just had an answer already! At least then she wouldn’t be so flustered. 

Pacifica paused a dozen yards from the front door as she really thought about what she was doing. What the hell did she expect to find? Them making out right inside the door? Fat chance. And what if she found nothing? That wouldn’t necessarily mean there wasn’t anything going on, just that she hadn’t found anything. She was really awful at this investigation stuff. 

She decided to just leave, her earlier bravado draining away. At least she’d gotten further than before. Maybe next time she’d have a better plan than simple impulsiveness could provide. She gave a sigh of frustration, and was about to turn around to head home when she heard a distant laugh.

Snapping her head in its direction, Pacifica caught sight of Mabel running backwards from the side of the Shack at varying rates of speed. She was moving such that every time her following brother dodged forward to grab her she was out of reach, yet never moving too far that he would give up as the they drifted towards the treeline. 

That was it. The playfulness that somehow felt different from what she saw in other siblings. Pacifica could never be totally sure about what was different exactly, but she swore it was there. In this case, it was the fact that he was clearly trying to grab her. How many things can you do when you’ve grabbed someone you’re chasing? 

Still, it wasn’t quite evidence, just an assumption unless she saw something more. What if they just ended up wrestling? Siblings do that. Of course, that kind of contact would only add further questions. Point was, she needed more. She swiftly went after them, hoping they would believe the woods provided them privacy for something more than a game of chase. 

She was never good at being sneaky, and much worse at it in nature, but Pacifica tried not to make too much noise while she fumbled in the direction the Pines twins had gone. It was more flailing through brush than anything resembling tracking and she wasn’t really paying attention to where she was going. Pacifica faintly recognized that she could get completely lost as she held onto her wild hopes of finally having an answer. 

Pacifica paused to breathe a bit after about 15 minutes of battling flora. She’d come to a small clearing and it seemed like a good place to rest before continuing. Her clothes were significantly less presentable than before she’d entered the woods, what with twigs and sap stains and the like. She was starting to regret being so impulsive since she had no idea if she was anywhere close to the twins. 

Fortunately, she had a stroke of luck. She heard a shuffling nearby and looked up to see Dipper and Mabel emerge from a bush on the other side of the clearing. She quickly dove back into the brush on her side, looking back to see if they noticed her. They hadn’t, more focused on their game, and Pacifica breathed a sigh of relief. She moved to get to a more comfortable spot, kneeling behind a short bush to peer between it and its neighbor. A laughing cry struck her ears just as she finished adjusting. 

“Nooooo! You got me!” 

Dipper had indeed finally caught her, his hand around her wrist. Mabel made no effort to escape as Dipper yanked her back to him. He let go, only to snatch her upper arms and glare in a menacing, yet goofy way. 

“Muahaha!” he laughed. “You’re mine now!” 

“What, what are you going to do to me?” Mabel whimpered. 

“Hm, my sharks haven’t had human in a while,” Dipper mused, Mabel gasping. “But it’d be a shame to send such a beautiful woman to her death.” 

Pacifica bit her bottom lip so she wouldn’t scream. That, that had to be proof! He called her beautiful! But, couldn’t it just be a compliment or something? They were doing some sort of roleplay game after all. Even though she was pretty positive about this, the little uncertainties still nibbled at her. 

“Yes, very beautiful…” Dipper said, releasing one arm to stroke the back of his hand gently across her cheek. “Perhaps I’ll make you my concubine.” 

“N-no, I don’t want to!” Mabel protested. 

“I suppose I’ll have to convince you then.” 

Dipper released her arm, his hand shifting to the small of her back and pulling her to him. The one at her cheek flipped to cup it as he leaned in. Pacifica clapped her hands over her mouth, her eyes as big as dinner plates when the twins lips came together. Any remaining uncertainties had finally been blown away. 

The kiss lingered a bit, then Dipper pulled away. Not too far, though, just enough that they could look into each other’s eyes for a brief moment before coming together again. This second one was a bit deeper, and Mabel slowly fell back under Dipper’s pressure while his hands moved to her hips to keep her steady. Eventually, she hit a tree and they stopped. Leaning on it for support, she lifted her hands to grip Dipper’s vest. 

Pacifica was losing her goddamn mind. She had always believed it would be better to see it for real instead of in her mind’s eye, but it was even more amazing than she’d dreamed. Feeling hot, she realized she had to get this on record while she had the chance. Fumbling around, she produced her phone and hurriedly typed her way to the camera option. 

Raising it, she zoomed in, loving how the advanced lens provided perfect clarity and a better view of the action. First, a single shot, because they were fucking adorable in this position and she just had to have it in still. Next was video, of course, because she most definitely had to have it in motion too. They weren’t moving much, exactly, but the slight head turns, the tiny squints, the OH SHIT, Dipper putting his tongue in! 

This was escalating! Pacifica was glad she’d gotten her camera on to catch it. Mabel wrapped her arms around his neck to pull in even deeper, while Dipper ran his hands slowly up and down her sides. On one downward stroke, he continued on past her hips, reaching back to squeeze her butt. Mabel squeaked out of the kiss and the twins looked at each other, sharing a laugh after a few moments. 

Dipper gave a sly grin, “So… be my concubine?” 

Mabel looked contemplative for a second. “Noooooooo… I’m still not convinced,” she replied. 

Dipper raised an eyebrow, “I guess I’ll have to try harder.” 

She squealed as he shrugged her arms off his shoulders and spun her around. Mabel grasped the tree as Dipper took her hips and leaned against her. He whispered something in her ear, but Pacifica was too far away to hear it. Mabel blushed and giggled a little, bopping her butt backwards into his pelvis lightly. From the position and actions, Pacifica had strong suspicions about what she was soon going to see. 

Suspicions instantly confirmed as Dipper slid his hands up Mabel’s stomach before passing over her chest. Mabel sighed and pressed back against him, her hands falling backwards as she tried to provide better access to her body. Pacifica noticed slight bumps in the fabric and realized that Mabel probably wasn’t wearing a bra. 

She nibbled her lip and muttered to herself, “Come on, come on…” Her eyes went wild as she got what she wanted. “Yeah, that’s it… grab that sweater…” 

Dipper lifted the hem of the sweater up Mabel’s stomach. Hesitating just as he reached the bottom of her breasts, he continued lifting, but at a much slower rate. Mabel’s mid-sized “girls” (as she liked to call them) were dragged up by the friction of the clothing. Ultimately reaching an apex moment, Pacifica held her breath while they quivered a bit as Dipper paused. After a few seconds anticipation, he tugged up again and Mabel’s boobs fell downward, bouncing a little from the force of the fall. Pacifica’s loud sigh as she let out her breath was thankfully covered up by a similar one Mabel gave at the same time. 

She shivered as she watched the boy’s hands travel about his sister’s skin. The hand that wasn’t holding her phone began mimicking his moves on her own body, though her clothes mitigated the pleasure to a level below what Mabel no doubt felt with the direct contact. Of course, they were both wearing skirts. So when Dipper’s hand traveled south to lift it and slip inside Mabel’s panties, Pacifica was quite able to match him. 

Moving her thong aside, a twinge shot up her as she touched her soaking lips, her eyes briefly unfocusing. She was a once-a-day kind of girl and had fingered herself hundreds of times in hundreds of ways. But nothing came close to how this felt right now, not even when she’d fantasized about being in just this sort of situation. The real sight was sooo much better than imagining it. Her eyes rolled up a bit as she slipped a finger inside herself. 

Her mind snapped back and she shook her head, refocusing on the twins. That was twice now she’d stopped watching, and in a very short span of time to boot. She didn’t want to miss a second of it even if she was recording. This could be her only chance to see it live, after all. 

Still, it wasn’t easy to keep a steady eye as she rubbed inside herself. What helped was wondering just how Dipper was doing it exactly. Mabel was moaning softly, her hand lightly stroking his forearm in encouragement as his wrist moved about with his ministrations. Pacifica wished she could keep mimicking him, but the angle and clothes blocked her view of the hand itself so she had to be satisfied with her best guesses. 

Between the hiccups of pleasure that interrupted her thoughts periodically, Pacifica wondered why she wanted to do to herself what he did to Mabel so badly. Did she want Dipper to touch her the same way? Mabel might not have the same weak points as her, who could say if it’d feel as good? And anyways, she didn’t feel like she really wanted Dipper to do anything to her outright. The brief flash of such an image in her mind was an irritating distraction from what she could be watching, so she brushed it away. 

Perhaps it was just her way of being a part of it. She took a few moments to imagine her pussy was not actually hers, but Mabel’s, attempting to inject a mental disconnect between the sensation she felt below from the sensation in her fingers. It didn’t work, instead having the opposite effect as she flinched. Her mind succeeded at separating the two feelings to an extent, but didn’t divorce the sense of pleasure she felt from either, resulting in a double-barreled blast to her nervous system. Her hand flung up to cover her mouth as she tripped into an unexpected orgasm. 

Gasping quietly as she came down, Pacifica felt amazed that her phone arm had steadfastly stayed in place, still recording the twins as Dipper stepped backwards so Mabel could slide down the tree and bend over. Through the fuzziness clouding her vision, she registered this sight and sighed heavily to try and release some of the heat quickly rising within again. This ride wasn’t over yet. 

She stood and moved to lean against a tree, making herself blatantly obvious if either of them cared to look over. Not too much of a worry as Dipper unfastened his pants and settled his cock between Mabel’s cheeks, her skirt and panties shuffled in opposite directions to provide him clear access. Pacifica switched her phone to the other hand to give her aching arm muscles a bit of relief after staying up so long. They had one task to do before resting, though, and she ripped her thong off, sick of bothering with its interference. 

She took a few moments rest as she watched Mabel grind up and down against her brother. Dipper stepped back a bit and his penis fell between her legs and out of Pacifica’s sight. It soon returned when he began moving back and forth a little, holding his shaft against her and lubing himself on Mabel’s lips without entering her. Mabel looked back at him and he smiled. 

“So, have I convinced you to be my concu-” 

“Shut up and fuck me!” Mabel commanded. 

Dipper barked out a laugh, then began easing himself inside his sister. As flesh gradually enveloped flesh, both twins closed their eyes. Pacifica watched how their faces showed little flickers of movement as they concentrated on the feeling of their union. How love shone in their eyes when they opened them once Dipper was fully inside. How Mabel had to turn away when he began moving, releasing a breathy sigh as she did so. 

Pacifica’s free hand drifted down to pull the hem of her skirt up and tuck it so it stayed as such. Her destroyed thong discarded to ground left her bare nethers exposed to the world. She tracked lazy circles on her skin, absentmindedly sliding closer and closer to her slickened sex while she watched the twins began quickening their pace. 

Mabel was breathing heavily as her brother moved into her again and again, a soft *whap* each time their hips met. Dipper had a look of concentration on his face, his gaze fixed on the back of Mabel’s head. Pacifica wondered if he was doing math in his head to last longer. It seemed a very “Dipper” thing to do. 

Such speculations were immediately swept away as her fingers reached their destination. Eyelids fluttering lightly, she took a soft breath in as she circled her clit. Watching Dippers thrusts, though, she had a different idea than idling around her button. She slipped two fingers inside herself, pulling them out and pushing in again as she worked her timing to match his. Soon enough, she moved at the same pace and a bit of drool leaked from her mouth as the similarity of movement made her feel like she was getting fucked and doing the fucking all at once. 

She didn’t know where to look exactly, the whole erotic scene in front of her a cornucopia of desirable choices. She started at Dipper’s butt, admiring it’s shape and how the muscles flexed with each thrust. Her eyes scanned over to his dick next, barely visible for brief moments, but just enough that she could see a light sheen of Mabel’s fluids upon it. Moving on, she saw the other girl’s ass ripple a bit every time she slammed backwards to meet her brother’s hips. Pacifica finally settled on Mabel’s breasts, hypnotic with their sway as they hung from her body. 

Fortunately, Pacifica no longer had to worry about where to look when Dipper leaned forward and took Mabel’s shoulders in his hands, pulling her upright. It likely wasn’t the first time they’d done this position, since Mabel deftly arched her back away from him, keeping the angle of her hips such that his cock stayed inside her. 

No longer supported by the tree, Dipper took its place with one hand on her hip and another wrapping under her arm to squeeze a boob. Mabel used that arm to reach back and pull Dipper’s head to her, turning her own to meet his lips. The position was awkward, and Pacifica felt sure that the physical pleasure was diminished greatly, but it was also undoubtedly erotic and passionate. The sight of them together like that was too much and she finally lost her grip on her phone. 

It was a miracle she’d held it up so long in the first place, not that she really gave a shit at the moment. The second it left her hand it was out-of-sight, out-of-mind. Instead, she put the hand to better use immediately, slipping a few fingers into her mouth and running her tongue around them as she desperately tried to maintain her mimicry of the twins actions. 

On that note, the aforementioned awkward position they had taken also threw off her timing as Dippers thrusts became haphazard and unpredictable. She fuzzily decided she might as well just go back to rubbing her clit, even if it could push her to an orgasm first despite her growing desire to share one with them. And yet, perhaps that was the right thing to do if she wanted to achieve that goal. 

It might’ve been because she was lust-drunk watching them fuck, but she swore she could tell they were both very close. She’d turned out to be right about them committing incest, even more right than she thought, in fact, so it was plausible she was right about this as well. Pacifica didn’t dwell on the matter, simply deciding she was right in her assumption as she sucked harder, rubbed faster, and stared furiously at them while they finally broke their drawn out kiss. 

“D-d-hah!-Dipper…” Mabel squeaked out, looking into his eyes desperately before she fell back onto the tree. Dipper ensured it was  a gradual and not abrupt fall. He then immediately quickened his pace, slamming her harder than before with wet slaps of skin meeting skin echoing in Pacifica’s ears. 

This feels great. I’m so close. Right there. You’re the best. I love you. 

A myriad of unspoken sentences spun through Pacifica’s head as she couldn’t help but wonder what Mabel had meant simply saying his name in a way she knew he understood. Her eyes were wild as she accepted them all as true. Lust, love, friendship, she didn’t care how these two were together, she just loved seeing it. She bit her fingers as she felt herself about to hit the edge from those thoughts. 

“Ah, fuck! Ma-” 

Pacifica missed the rest of Dipper’s utterance, Mabel’s scream as she came drowning it out. She knew what he was getting at, regardless. Him shoving himself in his sister as deep as he could go, hunching over with a grunt; it wasn’t exactly hard to tell he was filling her with his seed. How perfect for them to cum right at the same time. 

Pacifica’s fingers sloppily fell out of her mouth, catching the neck of her top by muscle memory and yanking it down as her own orgasm rocketed through her. Her eyes rolled back, faintly registering a flickering darkness and light as her eyelids flitted unconsciously. Her hips bucked slightly against her hand, as if she could somehow get the nonexistent dick deeper inside of her. The action and her shivering legs almost certainly would’ve caused her to fall down if not for the tree she leaned upon. 

It took a minute for Pacifica to come down to a point where she could functionally think. Her head lolled to the side in exhaustion as she peered forward. The twins had extracted themselves from each other, their own orgasms apparently not so incredibly draining as her own. They were quite capable of standing and had embraced in a long, slow kiss. Goddamn, they were adorable. 

Pacifica’s muddled thoughts rallied to bring the realization she should probably get out of here. She needed to get her phone though. Looking about, she spotted it on the ground. Leaning over to pick it up, she instantly lost her balance on her tired legs and fell over, shaking a bush. She heard the twins gasp and quickly stood up. 

“I’m okay! I’m okay! Just dropped my camera- I mean phone, haha! she announced, holding it aloft after she popped up behind the bush. 

There was no reply, and she noticed their eyes were huge. Her thoughts, sluggish as they were, finally caught up and she knew she’d been an idiot. They were still embracing, and Dipper noticeably squeezed Mabel tighter, his eyes narrowing. An awkward few moments passed silently before he spoke. 

“What do you want, Pacifica?” 

“Want?” Pacifica replied in confusion. 

“You took pictures, or a video. Don’t lie. You called it a camera first,” Dipper said steadily, little warbles slipping into his syllables and giving away his true nervousness. “What do you want for it?” 

Pacifica still felt a bit confused, probably because of the raucous trip her mind had gone through just now. She stepped out of the brush and approached them. She noticed a look of shock on their faces as they both looked her up and down. Oh yeah, her pussy was just out there for anyone to see. Her hair was probably a mess too, since it had been between her and the tree. And the random bits of forest her clothes had collected during this little adventure. She must be quite the picture of disheveledness. A good match for them, she figured, seeing as they hadn’t bothered to fix themselves up either.

“I don’t understand?” 

“You’re, you’re blackmailing us… aren’t you?” Dipper asked, his face scrunching with bewilderment. 

Pacifica stared a second, then finally realized what he said with a gasp. Why the hell wouldn’t they think she was blackmailing them? She’d just videotaped them fucking, what else was there to do with that kind of evidence? 

Well, she’d certainly answered that question today. She saw how the twins both kept looking her up and down, trying to comprehend her appearance in the context of their obvious fear of discovery. They must have caught onto what she’d been doing by now and were having difficulty processing such an unexpected turn of events. She was throwing them a hell of a curveball with her weirdo fetish. 

“No, I wasn’t going to blackmail you, this was for me,” she finally answered. The wheels in her brain rapidly spun as Dippers accusation spurred new ideas. “I didn’t intend to blackmail you, I mean, but since you brought it up… maybe I will.” 

Panic filled their eyes. Pacifica instantly felt bad. She was just trying to be a bit theatrical in her request, not mean. It was easy to forget their perspective on the matter, from which her motivation was a complete mystery and could very easily be hostile. 

“I-I didn’t,” she said hurriedly, “I was just trying to- Ugh! Look, I’ll,” her voice dropped, “I’ll delete it. Right now. But you have to let, um… let me watch again…” 

Her face burned furiously as she trailed off. Oh god, she’d actually done it. She’d asked to watch them fuck. Her mind must still be jumbled to ask that. She was starting to feel really bad about how she’d handled this. The “blackmail” thing was a joke. She had assumed they’d say yes, but what if they didn’t like being watched? She was just being selfish, a typical Northwest. 

She felt ashamed and resolved to just leave and delete the evidence. Maybe they could pretend this hadn’t happened. Perhaps if she offered to help cover their relationship up, they’d forgive her. She glanced at them as they conferred with each other in whispers, flinching when they looked back at her. 

“Hey, Pacifica,” Mabel said. “We’re not really sure about this, but we’re not exactly against it.” The blonde cocked her head as she listened. “Sooo, we told Soos and Melody I had a ‘girls night’ planned in a couple of days and they decided to book a night at the inn for a date of their own. The thing is, we knew Candy and Grenda are out of town that day… See where I’m going with this?” 

Pacifica lit up. They were inviting her to a night they’d explicitly planned to have sex. She fought to maintain her composure at the knowledge she could experience this all again. She failed. Chucking her phone as hard as she could against a tree, the device exploded into shards. The evidence of today’s events was now lost forever. 

After a brief pause to let the action sink in, she coolly said, “I’ll buy a new one and call you for details.” She turned to walk away, satisfied with her exit. 

“Pacifica! Your skirt!” Dipper called behind her. 

Oh yeah, she hadn’t fixed it yet. No wonder it felt so drafty down there. So much for leaving gracefully. She shoved it down into place, then ran off, covering her embarrassment at the now awkward exit with her excitement for what was to come.


End file.
